Many structures, such as toys, buildings, and furniture, are assembled from modular components which are generally referred to as building blocks.
U.S. Pat. Nos. 3,005,282, 3,034,254, and 3,597,875 disclose stackable toy building bricks which are adapted for forming multi-layered or high-rises toy structures by interlocking of stacked building bricks. Such building bricks typically comprise a molded main body of hard plastics having an upper mating surface, a lower mating surface and side surfaces defines by a periphery. The upper mating surface comprises a plurality of cylindrical mating protrusions and the lower mating surface comprises a corresponding plurality of hollow cylindrical protrusions which cooperate with the side surfaces of the peripheral to collectively define mating receptacles for receiving the mating protrusions on the upper mating surface of a building brick immediately below in a press fitted manner to provide friction interlocking. While the mating protrusions are typically of a generally cylindrical shape, building blocks having prismatic but non-cylindrical upper mating protrusions are also known, for example in EP 1,464,369.
Modular building bricks are advantageous and have been widely used because they provide a high degree of freedom and flexibility to permit creation and construction of useful and aesthetic structures. However, it is noted that interlocking of building blocks to form a secured structure could be difficult.
In this specification, ‘building block’ includes toy building blocks such as those commonly referred to as ‘building bricks’, and non-toy building blocks such as modular components used for building, furniture, equipment or vehicle construction.